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Molecular communication has been an important topic of nanotechnology. The combination of multi-nanomachines to form nano-networks is one of the main methods for practical applications. This paper proposes a transmitter positioning method for Molecular Communication via Diffusion systems with a single transmitter and multiple spherical absorption receivers. Receivers count the number of received molecules and use the Levenberg-Marquardt method to estimate the distance of the transmitter to each receiver, and then obtain the transmitter position by using a multi-point positioning method. Monte Carlo simulations are carried out to evaluate the performance of the proposed method. The simulation results show that the proposed method can accurately estimate the position of the transmitter in short to medium communication ranges.

Nanozymes’ activities could be regulated by a simple and effective pH change in an in situ manner. In this work, for the first time, the peroxidase-like activity of Ni/Co layered double hydroxides (LDHs) was regulated via the alkaline-promoted reaction of fluorogenic substrate homovanillic acid and H2O2, and a promising tool for pH sensing was developed over the pH range of 8.3–9.6. As peroxidase nanozyme model, Ni/Co LDHs showed ease of preparation, low-cost, and water-solubility, which played an important role in this luminescence system. Based on the pH-dependent regulation of the Ni/Co LDHs activity, we constructed the bioassay platform for the determination urea, urease, penicillin G, and penicillinase with a wide linear range of 17–1000 µM, 3.3–270 mU mL−1, 3.3–1300 µM and 3.3–100 mU mL−1, respectively. This study not only demonstrated the alkaline-promoted modulation the nanozymes’ activities, but also established a facile approach to develop novel bioassays.